It is well known that fabrics and garments for "clean rooms" in the areas of microelectronics, medicine, pharmaceuticals, industrial ceramics and the film and sound recording industry are predominantly made of polyester filaments, which admittedly have an adequately low particle emission, but do not guarantee protection of the components, for example, sensitive microcircuits, sensitive integrated circuits and other sensitive semiconductors, against static electricity.
To reduce or eliminate the aforementioned defect, it is furthermore known that antistatic chemicals may be applied in the form of additives in detergents and rinsing aids or in the form of sprays on the wearing apparel. Admittedly, these chemicals reduce the cling effect of the wearing apparel to the body of the wearer, but they do not prevent the build-up of a high static charge on the surface of the wearing apparel. Moreover, such chemicals are not washfast.
Aside from a thin, narrow metal foil as a central layer, known metal laminated threads have a covering layer comprising a thin plastic film. For this reason, these threads are not suitable for the purpose mentioned, since only the thin edges of the middle metal layer are exposed, with which the static electricity cannot be dissipated adequately.
Admittedly, charges of static electricity are dissipated and dispersed by the use of metal fibers and metal threads in yarns. However, the fabrics manufactured therefrom have a negative effect on the particle emission, due to the hairiness of the yarns, and are therefore not suitable for "clean rooms".
Moreover, untextured monofilaments have been used, which achieve electrical conductivity owing to the fact that they have a plurality of electrically conductive particles, which are applied on or embedded in the surface of the monofilaments and thus impart electrical conductivity. These electrically conductive monofilaments are twisted together with at least one synthetic filament, which is neither textured nor electrically conductive. The fabric produced from these filaments and the wearing apparel produced therefrom admittedly are suitable for "clean rooms", since the particle emission is low an the electrical conductivity is good. However, they are susceptible to failure resulting from a mutual shift of the individual components when subjected to the action of mechanical forces. As a result, malfunctions of the conductivity of the fabric may arise due to damage to the conductive component.